It usually happened when he didn’t have something to distract him;
those few, blinking moments between sleep and wakefulness, or when
he caught a glimpse of a face and thought, for one hearts-stopping
moment, it looked familiar. He pictured it in his mind; the shock,
the joy, the moment when all the pain and guilt leeched away.

He never dreamed it would come true in a chip shop in London

And yet there she was. Her hair, dark and bobbed, cut sharply
against her neck; her face, rounded and young. She stood, leaning
against the counter and holding aloft a chip; staring at it with a
weary and clinical eye. The Doctor slowed his step; still not
certain, not sure.

“You know, I never really understood your fascination with this
planet,” she drawled, waggling the chip doubtfully. “Will it taste
any better with vinegar?”

A slow smile spread across his face as he slid the vinegar bottle
towards her. “Hello, Romana,” he said. “Long time, no see.”